1. Field of the Invention
The present invention relates to removable storage which enables life time management without a power supply, and to a semiconductor integrated circuit.
2. Description of the Related Art
With advancement of an information-oriented society, spread of a semiconductor memory as removable storage is remarkable. Among others, a flash memory is aboundingly used with spread of a digital camera or a mobile phone (see, e.g., Flash Memory Business Saizensen, Kyogyochosakai Publishing Co., Ltd. [Tokyo]). In the world of music distribution, a structure where a flash memory is accommodated in a package with a universal serial bus connector is aboundingly used because of facilitation of connection with a personal computer (a PC) and convenience in portability.
Contents distribution using a cable television or the Internet has already spread, and a contents distribution service can be used any time as long as a subscribing download terminal is present. However, even a subscriber cannot view/listen to contents by using, e.g., a personal computer or a mobile phone in a study room or an in-vehicle terminal if he/she does not have the download terminal.
Further, although a CD or a DVD that can be viewed/listened for a fixed period alone has also come into practical use, a medium after viewing/listening becomes a waste, and hence an environment problem remains. That is, there is a problem of a person who disposes this medium, thereby obstructing spread of the media.
Therefore, realization of removable storage and a semiconductor integrated circuit with a low bit cost that enables a contents provider to set a contents service period has been demanded.